With Gadaffi and Kim Jong Il gone, I think Putin is currently the world's #1 supervillain. He sends submarines to take control of the North Pole, he aims to control all of Europe's gas supplies, and he has set up an evil scheme to rule Russia forever in tandem with Dmitry Medvedev.

Ahmadinejad isn't a real supervillain, he just does what the priests tell him.

Castro scores a few supervillain points by never dying, always ready for a sequel, but apart from ruling his country with an iron fist he doesn't really do anything villainy these days.

Remus: Harry... I'm a werewolf.
Harry: Are you fucking serious?
Remus: Well yes, but I don't see how that applies here.